preparation

Preheat oven to 350°F with rack in lower third.

Heat oil in a wide 5-to 6-quart heavy pot over medium-high heat until it shimmers. Season brisket with 1 tsp each of salt and pepper, then brown brisket, turning once, about 8 minutes total. Transfer to a plate.

Reduce heat to medium. Add onions to pot and cook, stirring occasionally, until golden-brown, 12 to 15 minutes. Add carrots, celery, and garlic and cook, stirring occasionally, until golden,
10 to 12 minutes. Add vinegar, stirring and scraping up brown bits. Add stock and tomatoes and bring to a simmer. Return brisket
to pot, nestling it in braising liquid (liquid will not cover meat). Cover with a tight-fitting lid and braise in oven until fork-tender, 3 to
3 1/2 hours.

Cooks' note:
Brisket is best if made at least 1 day ahead (and up to
3 days) and chilled (covered once cool). Skim off fat before reheating.